[UNF] "Name Sticker" Goblin, [WHO] Coward // Killer, [WHO] Thijarian Witness (#11392)

* Add [WHO] Coward // Killer

* Add MTGO version of [UNF] "Name Sticker" Goblin

* Implement [WHO] Thijarian Witness

* Add NameStickerGoblinTest

* Fix Thijarian Witness, add tests (may need additional tests). Also adds a simple toString for MageObjectReference

* Don't spam the java garbage collector, add another test

* Replace non-ASCII characters in card text

* improve MOR toString

* Thijarian Witness fixed better, add AttackingBlockingWatcher in common

* cleanup from xenohedron's review

* Fix test, add warning not to use AttackingBlockingWatcher for static effects

* rename AttackingBlockingWatcher to AttackingBlockingDelayedWatcher to make it more obvious how it should be used, minor documentation changes
Simplify and rename Thijarian Witness Predicate

* add null checks

Mage/src/main/java/mage/MageObjectReference.java

@@ -100,6 +100,10 @@ public class MageObjectReference implements Comparable<MageObjectReference>, Ser
         }
     }
 
+    @Override
+    public String toString(){
+        return "("+zoneChangeCounter+"|"+sourceId.toString().substring(0,3)+")";
+    }
     public UUID getSourceId() {
         return sourceId;
     }

Mage/src/main/java/mage/watchers/common/AttackingBlockingDelayedWatcher.java

@@ -0,0 +1,70 @@
+package mage.watchers.common;
+
+import mage.constants.WatcherScope;
+import mage.game.Game;
+import mage.game.events.GameEvent;
+import mage.watchers.Watcher;
+
+import java.util.HashSet;
+import java.util.Set;
+import java.util.UUID;
+
+/**
+ * Stores attacking/blocking combat information but is only updated
+ *  1) as damage is dealt (combat damage or otherwise)
+ *  2) as a spell or ability starts resolving
+ *  3) Land playing or special action taken (just in case that then causes a static effect to kill)
+ * Thus the information is available after any involved creatures die
+ * and all dying creatures can see all other creatures that were in combat at that time
+ * WARNING: This information is NOT to be used for static effects since the information will always be outdated.
+ * Use game.getCombat() directly or one of the other combat watchers instead
+ * @author notgreat
+ */
+public class AttackingBlockingDelayedWatcher extends Watcher {
+
+    private Set<UUID> attackers = new HashSet<>();
+    private Set<UUID> blockers = new HashSet<>();
+
+    public AttackingBlockingDelayedWatcher() {
+        super(WatcherScope.GAME);
+    }
+    @Override
+    public void watch(GameEvent event, Game game) {
+        switch (event.getType()) {
+            case LAND_PLAYED:
+            case TAKEN_SPECIAL_ACTION:
+            case RESOLVING_ABILITY:
+            case DAMAGED_BATCH_FOR_PERMANENTS:
+                //Note: getAttackers and getBlockers make a new Set, so this is safe to do
+                attackers = game.getCombat().getAttackers();
+                blockers = game.getCombat().getBlockers();
+        }
+    }
+
+    @Override
+    public void reset() {
+        super.reset();
+        attackers.clear();
+        blockers.clear();
+    }
+
+    public boolean checkAttacker(UUID attacker) {
+        return attackers.contains(attacker);
+    }
+
+    public boolean checkBlocker(UUID blocker) {
+        return blockers.contains(blocker);
+    }
+
+    public long countBlockers() {
+        return blockers.size();
+    }
+
+    public long countAttackers() {
+        return attackers.size();
+    }
+
+    public static AttackingBlockingDelayedWatcher getWatcher(Game game) {
+        return game.getState().getWatcher(AttackingBlockingDelayedWatcher.class);
+    }
+}